ruby-core

Issue #16270 has been reported by zw963 (Wei Zheng).

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Bug #16270: Strange behavior on Hash's #each and #select method.
https://bugs.ruby-lang.org/issues/16270

* Author: zw963 (Wei Zheng)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: 2.6.3
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN
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Following is some example code:

``` ruby
sample_hash = {
    "246" => {
        "price" => "8000",
         "note" => ""
    },
    "247" => {
        "price" => "8000",
         "note" => ""
    },
    "248" => {
        "price" => "8000",
         "note" => ""
    }
}

sample_hash.each {|e| p e}
# following is p output content, we can see e is a hash element, and convert to a array object.
# this is expected behavior maybe, anyway, hash is same as a nested array.
["246", {"price"=>"8000", "note"=>""}]
["247", {"price"=>"8000", "note"=>""}]
["248", {"price"=>"8000", "note"=>""}]

sample_hash.select {|e| p e }
# Wired, why this time, e output different with each?
"246"
"247"
"248"
```

Following is source code for **each**

```c
static VALUE
rb_hash_each_pair(VALUE hash)
{
    RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
    if (rb_block_arity() > 1)
        rb_hash_foreach(hash, each_pair_i_fast, 0);
    else
        rb_hash_foreach(hash, each_pair_i, 0);
    return hash;
}
```

Following is source code for **select**

```c
VALUE
rb_hash_select(VALUE hash)
{
    VALUE result;

    RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
    result = rb_hash_new();
    if (!RHASH_EMPTY_P(hash)) {
        rb_hash_foreach(hash, select_i, result);
    }
    return result;
}
```

I don't  understand C well, don't know why lack of consistency for above two Hash method,
but, i think it is a little confuse me.

Thank you.






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